Compact roll of absorbent paper

ABSTRACT

A roll of wiping paper is obtained by winding a sheet of multi-ply absorbent paper around a core. The sheet includes at least a first and a second ply of absorbent paper, each with a grammage of between 15 and 30 g/m 2  and at least one of the plies incorporating a wet strength additive. The thickness of the sheet Ep being between 0.02 and 0.07 cm, the diameter of the core being less than 3.5 cm, the diameter of the roll being between 4.5 cm and 11 cm for a volume V of absorbent paper per unit length of the roll, and the absorbency A of the sheet in cm 3  of water per gram of paper being greater than 6 cm 3 /g. The ratio E=A/(Ep*V) of the roll is greater than or equal to 3.2.

CROSS-REFERENCE TO PRIOR APPLICATION

This application is a divisional application of pending prior U.S.patent application Ser. No. 14/126,136, filed Dec. 18, 2013, which isthe National Stage of PCT International Application No.PCT/EP2012/061522 filed on Jun. 15, 2012, which claims priority toFrench Patent Application No. 11 55244 filed on Jun. 15, 2011, which areall herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to the field of absorbent paper productsintended for wiping, in particular for domestic use.

BACKGROUND

Wiping paper is made with paper fibres and incorporates variousadditives including, in particular, an additive which increases its wetstrength. This type of additive, which will be referred to below as awet strength additive, forms a network through the sheet which does notaffect the paper fibres' capacity to absorb liquid, whilst replacing theinter-fibre links forming the paper which are broken in the presence ofwater.

The fibrous and chemical composition and the structure of a paperproduct intended for wiping are adapted accordingly. Compared with asimilar product intended for hygienic use, for example, it should haveboth greater tear resistance and a greater capacity to absorb liquid.

Wiping paper therefore incorporates, in chemical terms, an agent whichgives it wet strength and is structured so as to absorb a maximumquantity of liquid, in particular water. To achieve this, according toprior attempts, two or more plies of embossed paper are generallycombined. The embossed patterns and the deformation that they impart areselected to create the largest possible thickness whilst limiting theloss of mechanical strength caused by the embossing and resulting fromthe breaking of inter-fibre links along the zones which are subjected tothe embossing stresses. The paper is generally creped to give it theextendability required for the embossing.

There are essentially two ways in which the plies can be assembled. Thepoint-to-point combining method is obtained by embossing protuberanceson each of the plies, separately, in the same pattern, followed byfacing the protuberances of the two plies and gluing together their topswhich are in contact one another. In the so-called “nested” assemblymethod, the two plies to be joined are embossed with protuberances thathave patterns selected so that the protuberances of one ply are nestedwith those of the other ply, the join being made by gluing the tops ofone ply to the bottom of the pattern of the other ply. With thesecombining methods, the absorption is thus improved compared with thebase sheet owing to the spaces formed between the two plies. However,the height of the protuberances is limited by the loss of mechanicalstrength caused by deep embossing.

Wiping products for domestic use generally take the form of rolls with acontinuous sheet in the form of a strip which may be divided intorectangular shapes by transverse pre-cuts and is wound around a core.

SUMMARY

The dimensions of the rolls are now standardized, with a given diameterand width. Given the desired goal of absorption by paper manufacturers,the rolls have a high volume of empty spaces. It would, however, beeconomically and ecologically advantageous to reduce this volume whilstpreserving the properties of the product.

It is desired to produce rolls of wiping paper which are more compactthan rolls from the prior art but have a strip of paper of the samelength.

It is also desired to produce compact rolls with a sheet of absorbentpaper which substantially preserves the same properties as the sheetsfrom the prior art in terms of both absorption and tear resistance orimproves the latter.

A solution has been found with a roll of wiping paper obtained bywinding a sheet of multi-ply absorbent paper around a core, the sheetincluding at least a first and a second ply of absorbent paper, eachwith a grammage of between 15 and 30 g/m² and at least one of the pliesincorporating a wet strength additive, the thickness of the sheet Epbeing between 0.02 and 0.07 cm, the diameter of the core being less than3.5 cm, or less than 3 cm, and the diameter of the said roll beingbetween 4.5 cm and 11 cm, or between 4.5 cm and 9.5 cm for a volume V ofabsorbent paper per unit length of the roll, and the absorbency A of thesheet in grams of water per gram of paper being greater than 6 cm³/g.The roll is characterized in that the ratio E=A/(Ep*V) is greater thanor equal to 3.2.

This ratio expresses the fact that there is an optimum absorbency whilsthaving a reduced volume of paper.

In particular embodiments, the thickness of the sheet is between 0.03and 0.06 cm and the absorbency less than 16 cm³/g.

In certain embodiments, the sheet has a length of between 8 m and 30 mand the strip forming the sheet is precut along transverse separationlines into successive individual lengths; the number of individuallengths is between 25 and 300 and their length is between 100 and 300mm.

In certain embodiments, the plies of the sheet have first protuberancesdirected towards the inside of the sheet and at least 15% of the firstprotuberances of a ply are nested between the first protuberances of theother ply. The density of the first protuberances is then between 20 and90, or-between 30 and 60.

According to a first embodiment, the roll is formed from a sheet, atleast one of the plies of which has a density of at most 0.15 g/cm³, thesaid ply having first protuberances of the type obtained by moulding onan imprinting fabric of the papermaking machine on which the paper ismanufactured.

More particularly, the first protuberances of the plies have a height,relative to the base plane of the ply, of between 40 and 80% of thethickness of the ply and, according to another feature, the spacing in adirection between the first protuberances is at least equal to thelargest dimension of the first protuberances in the said direction. Thetwo plies are not calendered and have kept the pre-converting bulk.

The type of paper having such features is advantageously obtained by anon-compressive manufacturing method in which the sheet is dried atleast partly by a flow of hot air that is passed through the thicknessof the sheet. The sheet, after draining and with a suitable moisturecontent, is in particular deposited on an imprinting fabric that iswoven so that cavities are created on the surface. The sheet is mouldedon the fabric and matches the raised marking; the fibres are partlyoriented in a direction perpendicular to the plane of the fabric and aredisplaced relative to one another by the flow of hot air which isdirected perpendicularly to the fabric. The air removes at least some ofthe moisture from the sheet and fixes the fibres in position. When it isdetached from the fabric, which is referred to as an imprinting fabricin the industry, the sheet thus has protuberances which correspond tothe cavities of the fabric. The bulkiness of the sheet results partlyfrom the drying caused by the flow of air passing through the mass offibres and partly from the moulding on the imprinting fabric. Thegeometry of the moulded sheet depends on that of the imprinting fabric.

This means of manufacturing paper is commonly referred to as TAD(through air drying). The sheet obtained by this technique is bulkierthan a sheet manufactured using the conventional pressing dryingtechnique known as CWP (conventional wet pressed).

TAD may be combined with another drying method for creping the sheet.While still wet, the sheet is stuck onto a so-called Yankee drying rolland is then removed using a suitable blade.

According to another embodiment, the sheet is obtained from two embossedplies obtained using the conventional so-called CWP technique.

According to another feature, the plies are joined together, inparticular by gluing, along joining zones, the said joining zones havinga reduced thickness compared with that of the sheet and forming a cavityon each of the two faces of the sheet. In other words, the zones do notform any surface unevenness; they do not protrude from the surface ofthe sheet. The join enables the plies to be held nested in each otherand stabilizes the two-ply sheet. The joined zones are thin comparedwith the unjoined zones. They do not make the sheet thicker. In order toensure that the two assembled plies cohere together properly, thejoining zones are evenly distributed on the surface of the sheet. Theydo, however, take up less than 15% of the surface area of the sheet,0.2% to 7%, or 3% to 6%.

According to one feature, the absorption efficiency, equivalent to theratio of the absorbency, measured in cm³ of water absorbed per gram ofpaper, to the density, measured in cm³ per gram, is greater than one.This is a noteworthy property of the sheet which distinguishes it fromconventional embossed products. Attempts have indeed been made in theprior art to increase the thickness of the paper sheet by means ofembossing in order to improve absorption. The expression of anabsorption efficiency greater than one indicates that the embossing ofthe plies is limited to the joining together of the plies and that thethickness of the sheet has been reduced. Surprisingly, such a sheet hasa reduced thickness which allows it to be wound into a roll with asmaller diameter than rolls from the prior art, with the same fibrousand chemical composition, and at the same time preserves the overallabsorption properties. Only a slight reduction in absorbency, of about5%, is observed in comparison with the base sheet. Furthermore, giventhat the paper is not embossed at all or less embossed than anequivalent product in terms of fibrous and chemical composition from theprior art, the mechanical tear resistance properties are improved. Theimprovement for each of the plies results from the joining together ofthe plies.

The paper thus makes it possible to produce compact rolls. Thiscompactness is expressed by measuring the softness of the roll. In thiscase, it is less than 35, which is greater than that of rolls formedfrom very tightly wound strips and with no core, which are much lesssoft.

Also disclosed is a method for manufacturing a roll from a sheetobtained as follows:

-   -   Two strips of paper are provided, one for each of the said two        plies, the two strips being arranged relative to each other so        that the first protuberances face the other strip;    -   The first strip is embossed on an embossing roll with teeth by        applying a rubber roll; after embossing, the height of the        projecting part forming the raised marking is less than the        thickness of the strip of paper;    -   An adhesive is applied to the raised marking obtained on the        first strip;    -   The second strip is placed on the first strip whilst the first        strip is being held on the embossing roll, and a marrying roll        applied to the whole joins the two strips together; the        manufacturing method is characterized in that, on the one hand,        the pressure applied by the rubber roll and, on the other hand,        the pressure applied by the marrying roll allow two strips to be        joined together along the glued zones without protuberances        being formed on the face of the sheet against which the marrying        cylinder is applied. For TAD, the two strips are typically not        converted by calendering or another equivalent converting after        the paper was manufactured on the papermaking machine.

According to a first method for obtaining the sheet, the two strips areTAD paper.

According to another method for obtaining the sheet, one strip, such asthe first strip, is TAD paper and the other strip is CWP-type paper, thefirst protuberances of which are obtained by embossing.

According to yet another method for obtaining the sheet, the two stripsof paper are CWP-type paper and the first protuberances for the twostrips are obtained by embossing.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described in more detail with referenceto the attached drawings, in which:

FIG. 1 shows a schematic view in cross-section of a sheet for producinga roll;

FIG. 2 shows diagrammatically an installation which is capable ofmanufacturing a sheet;

FIG. 3 is a photograph of a sheet, in an exemplary embodiment, seen incross-section;

FIG. 4 is a photograph of a ply of the sheet in FIG. 3, seen from itsrough side;

FIG. 5 shows a softness measuring device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiment with a TAD-Type Sheet of Paper

FIG. 1 shows a schematic view in cross-section of a sheet 1 forproducing a roll, the thickness being shown on a different scale fromthe width. It consists of two plies 10 and 20 of high-quality absorbentpaper intended for wiping. In this embodiment, the paper is of the TADtype.

The paper contains a wet strength additive such as a PAE resin(polyamide epichlorohydrin).

On its face turned towards the inside of the sheet, each ply hasunevenness in the form of separate protuberances, first protuberances 13and 23, which extend in a direction perpendicular to the base of thesheet, the base having the reference numerals 11 and 21, respectively.These protuberances correspond with cavities on the opposite face 13′and 23′. This raised marking is obtained on the papermaking machine whenthe sheet, after it has been formed and drained and downstream from theheadbox, is deposited onto a so-called imprinting fabric which hasrecessed zones. The dry content of the sheet at this stage is between15% and 30%. The three-dimensional structure of the imprinting surfaceresults from an appropriate weaving of the threads of the imprintingfabric. The paper fibres deposited on this fabric, if they are not stilljoined together, are displaced by the flow of air passing through themand some of them assume an orientation which has a radial component; theshaping of the sheet to the raised marking of the fabric is fixed bydrying. The dry content of the sheet when removed from the imprintingfabric is about 80%. In the present example, the imprinting fabric iscommonly used to manufacture tissue paper. The fabric is chosen suchthat the density of the protuberances obtained on the sheet is between20 and 90 protuberances, or between 30 and 60.

The pattern of the first protuberances 13 and 23 on the two plies allowsthem to be nested. The top of a first protuberance on a ply fits betweenthe first protuberances on the other ply. The protuberances are nestedat least partially inside one another, at least 15% of them but possiblyas many as 40% depending on the imprinting pattern. The remainingprotuberances are crushed by the marrying roll. This nesting results ina thickness D of the sheet which is less than the sum of the thicknessesD1 and D2 of each of the plies. It may be observed that the thickness D1of the ply 10 is equal to the thickness d11 of the fibrous mass of thebase 11 plus the height d12 of the first protuberances 12. The same istrue for the thickness of the ply 20: D2=d21+d22. The protuberances ofthe two plies can be identical but also where the protuberances resultfrom markings on different imprinting fabrics. d11 can thus be equal toor different from d12, and d21 can be equal to or different from d22.

Method for Measuring the Protuberance Heights.

The height of the protuberances is defined by the height measuredbetween the surface of the ply at the base of the protuberances and thetop of the latter. The method for measuring the difference in height ofthe protuberances is defined below:

Commercially available equipment is used which is adapted for carryingout surface measurements of three-dimensional objects. It includes adevice for measuring the surface (marketed under the name Optotop/mpeIII), a three-dimensional imaging programme (marketed under the nameOptocat) and an image analysis programme (marketed under the nameToposurf).

The samples are placed with the “rough” side facing the light from the3D analyser so that the inner ply of the sheet can be examined. Eachsample is flattened as much as possible to prevent interferingdifferences in heights from being measured. The surface analysed is arectangle 20×16 mm. Light fringes are projected onto the surface. Thefringes are projected at the same frequency but they are phase-shiftedby π/2 from one pass to the next. The fringes are deformed on thesurface of the 3D object. The height of each of the points of thesurface of the object can be calculated by analysing the deformation. Asinusoidal signal is obtained which is processed by the Optocat program.The image is acquired by triangulation between the fringe projector P,the sheet and the digital camera.

The images are then processed by the Toposurf program. The image isfirst flattened to compensate for the optical deformations caused by thelens of the camera and then clipped to remove the extreme values (99.9%of data is preserved). A reference image is then obtained. Each pixel ofthe image is referenced in space and has values in the three axes.

The reference images are then processed using the ‘Extract a profile’function. This function allows a line to be drawn on the reference imageand a 2D height profile to be created using the straight line that wasdrawn. This profile is then extracted and a difference between the meanz of the upper points and the mean z of the lower points is calculated.

On the sheet manufactured with the abovementioned imprinting fabric, thedifference in height measured using this method is 0.186 mm+/−0.023 mm.

To measure the depth of the recesses on the “soft” side of the ply, thismethod gives a difference in height of 0.180 mm+/−0.021 mm.

Method for Measuring Thicknesses

In the present application, the thicknesses of a ply or the sheet aredefined and measured as follows:

A stack of twelve product samples is arranged on a stationary plate, afeeler in the form of a rectangular plate with a 10 cm² surface area ismounted on a sliding rod which can move perpendicularly relative to thestationary plate; the feeler is lowered onto the top of the stack at aspeed of 2 mm/s and then applies a pressure of 20 g/cm² to the sheet.The value of the distance separating the two plates is measured after 5seconds. The thickness is one-twelfth of the measured value.

According to another feature, the two plies of absorbent paper arejoined together along joining zones 25′; the two plies can be joinedtogether by a film of glue 26 such as a PVA glue. One of the two plies,20 in this case, has second protuberances 25 formed by embossing. Theheight of these protuberances is less than the thickness D of the sheet1 and does not form any unevenness on the opposite face of the sheet. Infact, in the joining zones the sheet has a first cavity next to theprotuberance on the ply 20 and a shallower cavity on the opposite face.The depth of the cavity on the opposite face can be flattened, as shownin FIG. 1.

The sheet is crushed in the joining zones. This reduction in thicknessresults from the manufacturing process, as will be seen when it isdescribed below.

A means of combining the two plies is illustrated in FIG. 2. The methodemploys an embossing unit 30 including an engraved roll 31, a roll madeof elastomeric material 32 interacting with the engraved roll 31 forembossing the strip of paper between the engraved roll and theelastomeric roll 32, a deflecting roll 33 parallel with the engravedroll, a glue applicator 34 with an applicator roll interacting with theengraved roll, and a marrying roll 35 interacting with the engravedroll. The engraved roll is provided with teeth 25 a forming a patternthat corresponds to the pattern of the joining zones that it is desiredto form on the absorbent sheet of paper.

The method is as follows: two strips of absorbent paper 10 and 20intended to form the plies of the sheet are guided, for example, fromrespective jumbo reels. The strip 20 passes between the engraved roll 31and the elastomeric roll 32 where it is embossed with the pattern of theprotrusions 25 a; the embossing pressure is sufficient to emboss thesecond protuberances 25 on the strip 20 but the pressure remainssufficiently low that the second protuberances 25 are barely higher thanthe first protuberances. It should be noted that the strip 20 isarranged in such a way that the first protuberances 23 are on the sameside as the second protuberances 25 of the engraved roll; the strip 20passes in front of the glue applicator 34 which applies a film of glueto the tops of the second protuberances 25. The strip 10 is guidedaround the deflecting roll 33 and placed on the strip 20. The firstprotuberances 13 face the first protuberances 23 of the strip 20. Thewhole is guided towards the marrying roll 35 which is made from a hardmaterial. The hardness of the marrying roll prevents the embossing ofthe two-ply sheet. The sole purpose of the pressure exerted by themarrying roll is to join together the two strips by the film of glue onthe second protuberances. When the strip 10 comes into contact with thestrip 20, at least some of the first protuberances 13 of the strip 10are positioned between the protuberances 23 of the strip 20 so that theyare nested between one another. Downstream from the marrying roll, thetwo-ply sheet obtained has the structure shown in FIG. 1.

The two-ply sheet is then guided towards a rolling-up station. Thesheet, which is wide, is first precut by a toothed blade actingcrosswise at regular intervals to form the tabs that join together twosuccessive individual lengths. The sheet is wound around a cardboardcore over a length corresponding to the desired number of individuallengths. Because the two-ply sheet is thin, the sheet does not need tobe pulled tightly to obtain a compact roll.

Once the roll has been wound, blades cut the roll into shorter rollswhich are then packaged, ready to be put on the market. The rollobtained is compact and has the same length of paper strip as a standardroll. It allows savings in terms of logistics, taking up less spaceduring transport and storage especially.

Exemplary Embodiment with a Sheet of TAD Paper

Base Sheet

Absorbent paper was manufactured by the TAD technique using animprinting shaping fabric. The paper intended for domestic use forwiping incorporates various additives, including a PAE-type wet strengthadditive.

FIG. 4 shows a digitized image of the inner face of the two plies whichhas been greyscaled: dark grey for the shortest zones and light grey forthe highest zones. It will be noted that the protuberances are separatezones regularly distributed on the surface of the sheet.

It has the following features:

-   -   Density: 0.0695 g/cm³, which is the ratio of mass per unit area        to thickness;    -   Mass per unit area: 21.7 g/m²;    -   Sheet thickness: 0.312 mm;    -   Density of the first protuberances (shaping fabric): 45+/−5 per        cm²;    -   Height of the protuberances: 0.200 mm+/−0.021;    -   Density of the protuberances per unit area: 0.436 cm²/cm²; and    -   Average surface area of the protuberances: 0.00458 cm².

The base sheet produced by the papermaking machine was processed usingthe method of an embodiment of the invention to obtain a two-ply sheet.

-   -   Density of the two-ply sheet: 0.09 g/cm³    -   Thickness of the two-ply sheet (finished product): 0.47 mm

The characteristics of each ply after assembly are:

-   -   Average thickness of the plies: 0.297 mm,    -   Density of the protuberances (shaping fabric): 45+/−5 per cm²,    -   Height of the protuberances: 0.186 mm+/−0.023,    -   Density of the protuberances per unit area: 0.216 cm²/cm², and    -   Average surface area of the protuberances: 0.00227 cm².

For the embossed ply, corresponding to the ply 20 in FIG. 1, thedifference in height, measured between the top of the secondprotuberances 25 of the tissue paper and the first protuberances 23 is0.019 mm. It can thus be confirmed that the top of the joining zonesdoes not protrude from the surface of the sheet.

It will be noted that the average thickness of the two-ply sheet is muchless than the sum of the average thicknesses of each of the two plies.

Comparative measurements of absorption were carried out on a productobtained in this way and a product from the prior art which is marketedby the present Applicant under the brand Okay, both on productsmanufactured on a pilot line and on products manufactured on anindustrial line.

1) Products Made on the Same Pilot Line (Same Embossed Patterns, SameRecipes: Fibrous and Chemical Compositions):

Strength measurements were carried out on the product in accordance withstandards EN 12625-4 (dry strength) and EN 12625-5 (wet strength).

Measurements of absorption were carried out in accordance with thestandard EN 12625-8.

OKAY Inventive Example Grammage (g/cm²) 0.00428 0.00426 Thickness (cm)0.072 0.047 Dry strength machine direction 389 492 MD (N/m) Dry strengthcross direction 319 464 CD (N/m) Wet strength machine direction 105 139MD (N/m) Wet strength cross direction 88 126 CD (N/m) Theoreticaldensity (cm³/g) 16.82 11.03 Water absorbency (cm³/g) 13.5 12.3Absorption efficiency 80% 111% (−24% vs (+7% vs tissue) tissue)

2) Products Made on an Industrial Line:

OKAY Inventive Example Grammage (g/cm²) 0.004232 0.00434 Thickness (cm)0.0804 0.051 Dry strength machine direction 375 581 MD (N/m) Drystrength cross direction 245 409 CD (N/m) Wet strength cross direction70 104 CD (N/m) Theoretical density (cm³/g) 19 11.08 Water absorbency(water - 14.6 11.75 cm³/g) Absorption efficiency 77% 106% (−20% vs (+9%vs tissue) tissue)

It will be noted that in both cases the absorption efficiency, the ratioof absorbency to density, is higher for the product of the inventiveexample. The embossing pattern has no effect.

FIG. 3 shows a photograph of a cross-section of the sheet, enlarged 10times. It will be noted that the majority of the first protuberances 13and 23 are nested inside one another. For a portion of the surface ofthe plies, the first protuberances cannot be nested perfectly.

The two plies are joined along a thin joining zone 25′. The joining zonedoes not project from either side of the sheet; cavities are present oneach of the faces of the sheet, along the join 25′.

It will also be observed that the two plies tend to move apart from eachother owing to the resilience of the paper. The join thus makes itpossible to keep the two plies in position relative to one another. Itis sufficient for the glued surface to be less than 15% or between 0.2and 7%.

Rolls of paper were manufactured by winding sheets of paper assembled inthis way around a core with a diameter of 27 mm. The winding was carriedout with only as much traction being exerted on the sheet as isnecessary to wind it on without tightening it.

The characteristics of the roll obtained in this example, compared witha roll from the prior art marketed by the present Applicant under thebrand Okay.

Inventive Okay Example Sheet length (mm) 235 235 Roll height (mm) 230230 Number of sheets 43 43 Diameter (mm) 106 77 Required space (cm²) 8847 Number of rolls per m² 113 214 Ratio of number of rolls versus Okay100% 189% Volume of roll (cm³) 2030 1071 Ratio of volume versus Okay100%  53%

The softness of the roll after formation was measured.

Measuring the softness or hardness, with reference to FIG. 6, consistsin sliding the roll R over the rod 61 which is mounted on a rigidsupport 60, is horizontal and is in the form of a spindle.

A feeler 62 in the form of a disc with a 30 mm diameter is arranged onthe roll, at the centre of the width. A gauge 63, in this case a ROCHone, is installed and the needle is zeroed; with this gauge onerevolution of the needle corresponds to 1 mm of displacement. A 1 kgweight 65 is placed on the tray 64 of the gauge. The amplitude of thedegree to which the roll is crushed is noted (two measurements are madeon the circumference of the roll). The softness or hardness is theaverage of the two measurements expressed in tenths of millimetres.

Thus, for the inventive example of rolls obtained according to theinvention, the softness measured is 20. By way of comparison, thesoftness of a product sold by the Applicant under the Okay brand is 90.

OTHER EMBODIMENTS

Also part of the invention is the production of a roll with a sheet ofpaper with plies which are pieces of paper obtained using a conventionalCWP-type manufacturing technique with compression of the sheet and thendrying on a Yankee drying roll, as well as creping. Each ply includes anembossed pattern with a protuberance pattern, known as micro-embossing,consisting of separate protuberances with an overall frustoconical orpyramid shape. The density of the protuberances is then greater than 30per cm².

In order to manufacture such a sheet, the installation in FIG. 2 ismodified by providing embossing rolls. For example, the roll can be anengraved roll with two patterns at different levels, enablingsimultaneous embossing on the ply of the two patterns of the first andsecond protuberances.

According to another embodiment, the sheet used is a hybrid sheet with aply of TAD paper as described above and a sheet of CWP paper on top ofit.

Rolls with a 7.7 diameter on a cardboard core with a 2.7 cm diameter aremanufactured. The quantity of paper wound onto the core to form the rollhad a volume V of 41 cm³ per unit length of the roll in cm.

The ratio E was calculated for three embodiments; a TAD sheet, a hybridsheet and a CWP sheet, all three with a thickness Ep of 0.05 cm, andwith an absorbency A as in the table below. To calculate E, the value ofA is divided by the thickness Ep of the sheet and then by the volume Vof paper on the roll per unit length. The calculated values of the ratioE are indicated in the table. It will be noted that it is greater than3.2.

The same calculation was carried out for a commercially availableproduct Okay made by the present Applicant and it was confirmed that theratio E was less than 3.2 (see table).

Roll Core Tissue/roll diameter diameter volume ex Grammage ThicknessAbsorption (cm) (cm) core (cm3) V (g/m2) (cm) Ep (cm3/g) A E Inventive7.7 2.7 41 42.6 0.05 12.3 6.0 Example TAD 2-ply Inventive 7.7 2.7 4140.9 0.05 11.6 5.7 Example hybrid Inventive 7.7 2.7 41 35 0.05 7.5 3.4Example CWP 2-ply Okay 10.6 4.3 74 42.32 0.0804 14.6 2.5

1-14. (canceled)
 15. A method for manufacturing a sheet forming a rollof wiping paper comprising the following steps: a. providing two stripsof paper, each having first protuberances, the two strips being arrangedrelative to each other so that the first protuberances face the otherstrip, b. embossing the first strip on an embossing roll which hasprotrusions by applying a rubber roll to form a raised marking, c.applying an adhesive to the raised marking obtained on the first strip,and d. placing the second strip on the first strip whilst the firststrip is being held on the embossing roll, and a marrying roll appliedto the whole joins the two strips together along glued joining zones,wherein the pressure applied by a rubber roll and the pressure appliedby the marrying roll allow the two strips to be joined together alongthe glued zones without protuberances being formed on the face of thesheet against which the marrying cylinder is applied.